Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 292207
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
308 PM PDT WED JUL 29 2015

.SYNOPSIS...STRONG UPPER LEVEL HIGH PRESSURE CONTINUES TO REMAIN OVER
THE REGION BRINGING ADDITIONAL WARMING TO THE REGION TOMORROW. THE
HOTTEST TEMPERATURES WILL LIKELY OCCUR ON THURSDAY. FRIDAY WILL BE
SIMILAR WITH ONLY GRADUAL COOLING EXPECTED THROUGH THE WEEKEND AND
THE START OF NEXT WEEK.

&&

.SHORT TERM...TODAY THROUGH SATURDAY...THE WELL ADVERTISED WARMING
HAS MATERIALIZED WITH SURFACE TEMPERATURES THIS AFTERNOON RANGING
FROM 10F TO 15F WARMER THAN THIS TIME YESTERDAY. VISIBLE SATELLITE
SHOWS CLEAR SKIES ACROSS THE REGION THIS AFTERNOON WITH THE EXCEPTION
OF A THIN BAND OF MARINE STRATUS MOVING SOUTH OVER THE WASHINGTON
COASTAL WATERS AND JUST ONSHORE ALONG THE LONG BEACH PENINSULA. ONLY
A FEW MINOR NUDGES TO THE OVERALL TEMPERATURE FORECAST FOR THE NEXT
FEW DAYS AS FORECAST MODELS REMAIN IN GOOD AGREEMENT WITH RESPECT TO
850 MB TEMPERATURES WARMING A FEW DEGREES TOMORROW...BEFORE STARTING
TO SLIGHTLY COOL WITH LOWERING 500 MB HEIGHTS INTO THE WEEKEND. THIS
MEANS THAT THURSDAY REMAINS ON TRACK AS THE WARMEST TEMPERATURES OF
THIS STRETCH FOR MANY LOCATIONS. HOWEVER...DESPITE SOME SLIGHTLY
STRONGER ONSHORE FLOW ON FRIDAY...THE COOLING TREND WILL BE
GRADUAL WITH TEMPERATURES REMAINING IN THE 90S INLAND THROUGH THE
WEEKEND. AS A RESULT...EXTENDED THE HEAT ADVISORY FOR THE LOWER
COLUMBIA/I-5 CORRIDOR IN COWLITZ COUNTY THROUGH FRIDAY EVENING. BY
FRIDAY AND SATURDAY...EXPECT SOME INCREASING MID/HIGH LEVEL MOISTURE
TO WORK INTO THE REGION FROM THE SOUTH. WITH LIMITED ELEVATED
INSTABILITY AND A WEAK SHORTWAVE EMBEDDED IN THE FLOW TO POTENTIALLY
SERVE AS A TRIGGER...ELECTED TO MAINTAIN THE SLIGHT CHANCE THUNDER
MENTION FOR THE LANE COUNTY CASCADES TO ACCOUNT FOR THE UNCERTAINTY
DESPITE THE FACT THAT THE BEST CHANCES FOR THUNDER WILL REMAIN
OUTSIDE OF OUR FORECAST AREA.CULLEN

&&


.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...12Z GFS AND ECMWF
BOTH SHOW THE UPPER LEVEL RIDGE REMAINING OVER THE REGION THROUGH
SUNDAY. TEMPERATURES WILL LINGER IN THE LOWER 90S...UNTIL MODELS
HAVE AN UPPER LEVEL TROUGH SET UP OVER SOUTHWESTERN CANADA BY
MONDAY...WHICH WILL BE A TRANSITORY DAY AS MONSOONAL MOISTURE CREEPS
NORTHWARD BRINGING A THREAT FOR CASCADE THUNDERSTORMS. THE 12Z GFS
SHOWS A DEEPER UPPER LOW THAN THE 12Z ECMWF...BUT OVERALL WE SHOULD
STILL SEE INCREASING ONSHORE FLOW AND A GRADUAL COOLING TREND
LASTING THROUGH THE MIDDLE OF NEXT WEEK. HIGH TEMPERATURES WILL
FINALLY DROP BACK TO NEAR NORMAL BY TUESDAY. THE LANE COUNTY
CASCADES WILL SEE THE MAIN THREAT FOR MOUNTAIN THUNDERSTORMS MONDAY
THROUGH TUESDAY...BUT COULD SEE SOME THUNDERSTORMS OVER THE N OREGON
CASCADES AS WELL. /27

&&

.FIRE WEATHER...A THERMAL TROUGH IS EXTENDING FROM SOUTHERN OREGON
INTO THE NORTH OREGON CASCADES THIS AFTERNOON. EXPECT THIS TROUGH
TO REMAIN OVER THE REGION THROUGH AT LEAST FRI...DRIFTING BACK
TOWARD THE COAST EACH NIGHT AND MOVING INLAND DURING THE DAY AS THE
INTERIOR HEATS UP. THIS PATTERN WILL BRING ENHANCED MIXING AND
INSTABILITY...WHICH COMBINED WITH THE VERY HOT AND DRY WEATHER AND
DRY FUELS WILL CREATE CRITICAL FIRE WEATHER CONDITIONS. BASED ON THE
LATEST MODEL GUIDANCE...DECIDED TO EXTEND THE RED FLAG WARNING
THROUGH FRIDAY AND TO INCLUDE THE CENTRAL OREGON COAST RANGE...THE
SOUTHERN WASHINGTON CASCADES...AND ALL OF THE INTERIOR LOWLANDS. THE
THERMAL TROUGH IS MODELED TO FINALLY PUSH EAST OF THE CASCADES ON
SAT...ALTHOUGH THE TIMING OF THIS IS STILL SOMEWHAT UNCERTAIN. PYLE

&&

.AVIATION...EXPECT VFR CONDS FOR INLAND TERMINALS THROUGH 30/18Z.
EXPECT WIND GUSTS AROUND 20 KT THIS AFTERNOON AND EVENING IN
RESPONSE TO THE DAILY STRENGTHENING OF THE SURFACE THERMAL TROUGH.
STRONGEST GUSTS WILL BE ALONG THE COAST WHERE THEY MAY APPROACH 25
KT AT TIMES.

BAND OF COASTAL STRATUS ALONG THE WASHINGTON COAST WILL DRIFT
SOUTH TO ALONG THE NORTH OREGON COAST THIS EVENING. HAVE SOME
CONCERNS IT WILL MOVE CLOSER TO SHORE AS THE SURFACE THERMAL
TROUGH MAKES AN INLAND DRIFT THIS AFTERNOON. KAST WOULD LIKELY
STAY SCATTERED BUT AM ONLY HAVE MODERATE CONFIDENCE. IF THE
STRATUS DOES HIT THE TERMINALS THIS EVENING THEN EXPECT IT WILL
DRIFT OFFSHORE BY LATE EVENING AS THE THERMAL TROUGH DRIFTS TO
ITS OVERNIGHT POSITION ALONG OR JUST OFFSHORE.

KPDX AND APPROACHES...VFR CONDS. GUSTY NNE WINDS AROUND 20 KTS
BETWEEN 20-04Z. NEAR REPEAT FOR THURSDAY. /JBONK

&&

.MARINE...TYPICAL SUMMER TIME PATTERN WILL CONTINUE FOR THE NEXT
SEVERAL DAYS WITH NORTHERLY WINDS INDUCED BY THE SURFACE THERMAL
TROUGH HAVING SET UP ALONG THE NORTHERN CALIFORNIA AND SOUTHERN
OREGON COAST. NORTHERLY THERMAL TROUGH GRADIENTS AT THEIR STRONGEST
TODAY. WINDS HAVE BEEN A BIT SLOWER TO RESPOND TODAY PER MODELS
BUT STILL HAVE REASONABLE CONFIDENCE SMALL CRAFT CRITERIA WILL
EASILY BE MET BY LATE THIS AFTERNOON THROUGH THIS EVENING. BUOYS
HAVE BEEN HAVING A CHALLENGING TIME DETERMINING WHICH WAVE TRAIN
IS DOMINANT. THEY HAVE BEEN WAFFLING BETWEEN THE SHORTER CHOPPY
WIND WAVE DRIVEN PERIODS AND THE LONGER MORE DISTANT SWELL
PERIODS. GIVEN THE CONTINUED POTENTIAL FOR SQUARE SEAS... WILL
CONTINUE WITH THE ADVISORY FOR HAZARDOUS SEAS BUT DID EXTEND THE
CENTRAL OREGON WATERS THROUGH NOON TOMORROW. EXPECT A MORE
DEFINED TREND SHOULD BECOME APPARENT BY LATE TONIGHT.

LITTLE CHANGE IN THE OVERALL PATTERN THROUGH THE NEXT SEVERAL
DAYS ALTHOUGH SEAS SHOULD EASE ACROSS THE NORTHERN WATERS WITH
TIME. /JBONK

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 11 PM PDT FRIDAY FOR ZONE 603-ZONE 604-
     ZONE 605-ZONE 606-ZONE 607-ZONE 608.

     HEAT ADVISORY UNTIL 9 PM PDT FRIDAY FOR CENTRAL COAST RANGE OF
     WESTERN OREGON-CENTRAL COLUMBIA RIVER GORGE-CENTRAL
     WILLAMETTE VALLEY-COAST RANGE OF NORTHWEST OREGON-GREATER
     PORTLAND METRO AREA-LOWER COLUMBIA-SOUTH WILLAMETTE VALLEY-
     UPPER HOOD RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

WA...RED FLAG WARNING UNTIL 11 PM PDT FRIDAY FOR ZONE 604-ZONE 660.

     HEAT ADVISORY UNTIL 9 PM PDT FRIDAY FOR CENTRAL COLUMBIA RIVER
     GORGE-GREATER VANCOUVER AREA-I-5 CORRIDOR IN COWLITZ COUNTY-
     WESTERN COLUMBIA RIVER GORGE.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 3 AM PDT FRIDAY FOR COASTAL
WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT THURSDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR
OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL NOON PDT THURSDAY
     FOR COASTAL WATERS FROM CASCADE HEAD OR TO FLORENCE OR OUT 60
NM.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.


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